President Trump officially entered office Friday, erasing mentions of climate change from the White House website and replacing them with vows to increase fossil fuel development.

But Trump has yet to take the immediate action he promised on the campaign trail to reverse the Obama administration's Clean Power Plan.

The rule — which is on hold under a Supreme Court stay — could take years to unravel, although Trump could soon issue an executive order directing U.S. EPA to consider the Clean Power Plan illegal and stop any work related to the regulation.

The U.S. Court of Appeals for the District of Columbia Circuit could also determine whether the Clean Power Plan is legal any day now. Then a Supreme Court review could keep the plan in limbo even longer.

Meanwhile, Trump's pick to head EPA, Scott Pruitt, in a congressional hearing last week may have given some insight into how he could replace the regulation.

Pruitt said he accepts that EPA has a legal obligation to regulate CO2 emissions. He disagrees with how the agency has decided to limit carbon from power plants, though (Climatewire, Jan. 18).

Legal arguments Pruitt and other states have highlighted to challenge the Clean Power Plan outline what he thinks might be more in line with how he interprets the law (Climatewire, Sept. 28, 2016).

EPA set state carbon standards by examining how power companies could use less coal and more natural gas and renewable power. Pruitt's team has argued the agency should have looked only at efficiency improvements that individual power plants could achieve.

Replacing the rule might be a sounder legal strategy than just eliminating it, but it could take years. Coal plant efficiency improvements also would have a limited impact on emissions, and environmental advocates would challenge any laxer version of the regulation.

The nation's electric utilities aren't waiting around for the Trump administration to move ahead with the various steps it may take to undo the carbon rule.

Since 2005, carbon emissions from the power sector are down 21 percent, according to the Edison Electric Institute, the lobby for investor-owned utilities.

And the industry has announced the retirement of 82 gigawatts of coal plants between 2010 and 2024, an EEI spokesman said.

"It's clear that the courts have given the EPA the right to deal with carbon in a certain way," said Southern Co. CEO Tom Fanning, who is also chairman of EEI, in an interview after the election.

He said his industry would have no problem accepting a revised rule that limits CO2 reduction to "inside the fence line" of a generating unit.

In any case, the Clean Power Plan as it is written now is unlikely to ever take effect.

This week

The Senate continues to consider Trump's Cabinet nominees this week. Over the weekend, two of the Republican senators who had been considering opposing Rex Tillerson to run the State Department voiced their support. Sens. John McCain (R-Ariz.) and Lindsey Graham (R-S.C.) said they will vote to confirm Tillerson, the former CEO of Exxon Mobil Corp.

That leaves Sen. Marco Rubio (R-Fla.), whose vote is needed to advance Tillerson from committee consideration. Rubio tweeted Thursday that he still had "serious concerns" about the nomination but would decide soon.

On Thursday, the American Enterprise Institute holds a discussion about "the policy analytics of a carbon tax."

In case you missed it:

Trump took the reins, painting a grim portrait of the United States in his inaugural speech and laying out a basic direction for energy policy on the White House website (Greenwire, Jan. 20).

The Trump administration scrubbed references to climate change and the Council on Environmental Quality from its website (E&E News PM, Jan. 20).

Scientific American is part of Springer Nature, which owns or has commercial relations with thousands of scientific publications (many of them can be found at www.springernature.com/us). Scientific American maintains a strict policy of editorial independence in reporting developments in science to our readers.